1. Field of the Invention
The present invention relates to an inspection apparatus and an inspection method for light emitting devices, and in particular, it relates to the inspection apparatus and the inspection method for inspecting optical properties of the light emitting devices such as LED devices on an expanded wafer.
2. Description of the Related Art
In inspecting semiconductor devices formed on a wafer, it is a major challenge how to increase the number of inspection objects per unit time, in order to bring down inspection costs. However, on the expanded wafer, after the semiconductor devices are subjected to dicing and expanded on a tape, spacing between the semiconductor devices being the inspection targets is not constant and, further, is different on every wafer. Therefore, it is necessary prior to probing to acquire positional information of each semiconductor devices on every wafer, and this is a significant hurdle for increasing the number of inspection objects per unit time.
Particularly, in the case where the semiconductor devices to be inspected are light emitting devices such as LED devices, for instance, and where optical properties such as brightness and chromaticity of the devices are inspected, it is necessary to place a photodetector in proximity to the light emitting device to be inspected. By way of example, when an integrating sphere equipped with an optical detector is employed as the photodetector, its external dimensions are approximately the same as the expanded wafer, in general. Therefore, only one photodetector is allowed to be placed for one expanded wafer, which imposes a restriction that the inspection on the optical properties of the light emitting devices is able to be performed one by one only.
On the other hand, the Japanese Patent No. 4646271, for instance, which will be hereinafter referred to as the patent document 1, suggests an inspection apparatus for semiconductor devices separated individually by dicing process on a wafer. The apparatus here employs two probes, each of which is brought into contact with one semiconductor device, and inspects the electrical properties of two semiconductor devices simultaneously, thereby trying to achieve reduction of inspection time. Furthermore, it is said that this apparatus is also able to inspect optical properties by installing a photodetector.
However, in the apparatus according to the patent document 1, the photodetector is positioned to be able to detect only the vicinity of one of the two probes, and thus it is not possible to expect reduction of the inspection time as for the inspection of the optical properties.
The present invention has been made to overcome the drawbacks of the conventional technique as mentioned above, and an object of the present invention is to provide an inspection apparatus and an inspection method which are able to enhance efficiency of the inspection on the optical properties of the light emitting devices on an expanded wafer and to increase the number of inspection objects per unit time.